3. Write an equation for the circle whose center is at (9,0) and has radius 7.

x²+y²-18x+81-49 = 0

Step-by-step explanation:

For a circle with radius (r) and b center (a, b), the general form of the circle will be;

(x-a) ² + (y-b) ² = r²

According to the question, center given is (9,0) and radius is 7

From the value of the center,

a = 9 b = 0

Substituting this values into the general equation of the circle, this gives;

(x-9) ² + (y-0) ² = 7²

x²-18x+81+y² = 49

Re arranging

x²+y²-18x+81-49 = 0 which gives the required equation.